Poly(hydroxyalkanoic acid) (PHA) polymers such as poly(lactic acid) (PLA) can be polymerized from renewable sources rather than petroleum and are compostable. They have a broad range of industrial and biomedical applications. However, physical limitations such as brittleness and slow crystallization may prevent easy injection molding of PHAs into articles that have an acceptable degree of toughness for many applications. Extruded amorphous sheeting may also be too brittle for handling in continuous moving equipment without breakage.
It is desirable in the present invention to obtain a toughener for PHAs that allows PHA compositions to be easily melt-processed into a variety of articles with an acceptable level of toughness.
Japanese patent application publication H9-316310 discloses a poly(lactic acid) resin composition comprising PLA and modified olefin compounds. Examples of those modified olefin compounds are ethylene-glycidyl methacrylate copolymers grafted with polystyrene, poly(dimethyl methacrylate), etc. and copolymers of ethylene and alpha-olefins grafted with maleic anhydride and maleimide.